Human posture recognition and the measurement of body shape and position is critical to industries that develop safety equipment, perform skeletal modeling, conduct athletic performance research, research physiological response to various environmental conditions, ergonomics, and the entertainment (both video and gaming) industry. These industries currently rely on manual measurements using rulers and goniometers (see, e.g., US Army Publication TC_8-640), systems with inertial measurement units (IMUs) and discrete bend sensors, or visual camera-based systems. All three of these types of systems have significant challenges with respect to accuracy, efficiency, and complexity.
Measurement made using hand tools are subject to human systematic errors in the selection of measurement points and can be very time consuming. Additionally, this type of a measurement does not provide the ability to capture dynamic events, greatly restricting its usefulness.
Systems incorporating discrete bend sensing or IMUs suffer from massive amounts of data that need to be processed in order to determine the angles of the joints of the body. Once processed, these data cannot achieve the needed accuracies required in the industry and other applications. These types of sensors typically add weight to the user which may restrict movements of the user. Further, these types of sensors are bulky and interfere with the sensing system which requires further correction to the measurements.
Optical imaging solutions provide a more comprehensive and non-invasive identification of body shape, position, and posture. However, there are many disadvantages to imaging based solutions. Primarily, imaging based solutions requiring line-of-sight to the body being measured. Environments and applications that include obstructions or debris fields such as smoke, extreme humidity, and fog increase the difficulty or prevent accurate measurements. Moreover, a system of multiple cameras at all angles from the test subject is needed to fully identify desired measureands. This typically limits the motion and position of the user to a small, predefined area. Further, the subject of interest must remain in the focal area of the measurement system for optimal performance. These measurement systems present logistical challenges as they are not easily transported, and they must be highly calibrated to produce accurate results.
What is needed by the industry is a solution that overcomes these challenges, is portable, does not require line of sight to operate, and is highly accurate.